This is a proposal to use the National Death Index to determine the 10 year mortality status of the 361,662 middle-aged men screened in 1973-75 for the Multiple Risk Factor Intervention Trial, to complete a number of analyses on the relationship of diastolic blood pressure, serum cholesterol and cigarette smoking with death from cardiovascular disease and cancer, and to initiate new analyses on the seasonal variation of cardiovascular risk factors and endpoints. Over 17,000 deaths have been identified in this cohort to date using data from the Social Security Administration; death certificates have been collected and coded for approximately 14,000 of these deaths. We estimate that using only the SSA for vital status ascertainment, we will miss 25% of the deaths occurring in calender years 1982-85, a period of follow-up in which the mortality has increased due to aging of the cohort. Over the entire period of follow-up in which the mortality has increased due to aging of the cohort. Over the entire period of follow-up from 1974 the death ascertainment rate is estimated to be 80% if SSA is used. Our analyses with the 12,866 MRFIT randomized participants indicate that a 98% ascertainment rate would be achieved using the National Death Index for this critical time period, and the overall death ascertainment rate from 1974 to 1985 would be increased to 95%. With the complete 10 year follow-up of this large group of men analyses on risk factors from stroke and site specific cancer will be completed. In addition, this data set will be used to study the risks associated with isolated systolic hypertension, the seasonal and geographic variation in levels of serum cholesterol and blood pressure and the cyclic nature of cardiovascular disease. Using data from the Census Bureau (education and income levels by zip code), the socio-economic status of participants will be indirectly estimated and the coronary heart disease and cancer death rate difference between white and black men will be evaluated by social class. This data set on risk factors and mortality outcome is unique with respect to size and to the high level of quality control imposed during data collection. These aspects make the data particularly valuable for long-term follow-up and analysis.